论文总字数：24088字

摘 要

基于N-S方程，采用Pro/E和Fluent软件，将离心泵的蜗壳、叶轮以及进出口内的流体作为整体，通过数值模拟的方法分析在变固相体积分数的条件下过流部件的内部固-液两相流体的流动情况。探讨了固液两相流的假设模型，分析和预测了变固相体积分数的两相流动时泵内流体的压力、绝对速度、相对速度分布情况以及离心泵扬程和效率的变化情况。研究结果如下：

（1）离心泵入口处压力值很小，压力远离叶轮中心不断增加，这是因为叶轮的旋转使流体动能增大并不断转化为压力能，在出口处达到压力的最大值。当流体进入蜗壳，流体动能减少转化成压力能，所以蜗壳内压力高于叶轮内部的压力。随着固相体积分数的增大，蜗壳内流体压力受叶轮旋转影响增大，蜗壳内压力不断增大。

（2）绝对速度矢量方向基本垂直于叶片的表面，这说明固相颗粒受到来自叶片的力的作用，同时也加剧叶片磨损。在蜗壳附近的固体颗粒运动方向与蜗壳内表面相切，这说明固相颗粒在蜗壳和叶轮的作用下沿着蜗壳内壁面运动直到从泵的出口流出。通过比较各部分流体绝对速度数值，流体的绝对速度会随着固相体积分数的变大而有所降低，尤其是在叶片尾部，流体的绝对速度变化明显，其余部分基本相同。

（3）固体颗粒随着液相介质从泵的入口进入，在叶轮的带动下流体流速发生改变，流体中的固体颗粒在运动中会与叶轮发生碰撞并顺着叶片向叶片尾部运动，在蜗壳的作用下流体速度降低，压力增大，最后从出口处离开泵。不同固相体积分数工况下，流体相对速度的分布无明显变化。

（4）随着固相体积分数增大，介质间摩擦和碰撞更剧烈，从而水力损失变大，扬程减小；固相占比增加，流体质量流量增大，扬程增大。在颗粒直径较小时，前者对扬程的减少量小于后者对扬程的增加量，两者综合作用结果导致扬程随固相体积分数增大而增大。

关键词：离心泵 数值模拟 固液两相流 固相体积分数

Abstract

Based on the N-S equation, Pro/E and Fluent software are used to analyze the flow of solid-liquid two-phase fluid in the flowing parts under the condition of variable solid volume fraction by taking the fluid in the volute, impeller and inlet and outlet of centrifugal pump as a whole. The hypothetical model of solid-liquid two-phase flow is discussed, and the pressure, absolute velocity, relative velocity distribution and the variation of lift and efficiency of centrifugal pump are analyzed and predicted when the volume fraction of solid phase is changed. The results are as follows:

(1) The pressure value at the inlet of the centrifugal pump is very small, and the pressure keeps increasing away from the center of the impeller. This is because the rotation of the impeller increases the kinetic energy of the fluid and continuously converts it into pressure energy, reaching the maximum pressure value at the outlet. When the fluid enters the volute, the kinetic energy of the fluid is reduced and converted into pressure energy, so the pressure in the volute is higher than that in the impeller. With the increase of solid volume fraction, the fluid pressure in the volute increases under the influence of impeller rotation, and the pressure in the volute increases continuously.

(2) The direction of the absolute velocity vector is basically perpendicular to the surface of the blade, which shows that the solid particles are affected by the force from the blade, and at the same time, the blade wear is aggravated. The moving direction of solid particles near the volute is tangent to the inner surface of the volute, which indicates that solid particles move along the inner wall of the volute until flowing out from the outlet of the pump under the action of the volute and impeller. By comparing the absolute velocity values of each part of the fluid, the absolute velocity of the fluid will decrease with the increase of solid phase volume fraction, especially at the tail of the blade, the absolute velocity of the fluid changes obviously while the rest is basically the same.

(3) As the liquid medium enters from the inlet of the pump, the flow rate of the fluid changes under the drive of the impeller. The solid particles in the fluid will collide with the impeller and move towards the tail of the blade during the movement. Under the action of the volute, the fluid speed decreases, the pressure increases, and finally leaves the pump from the outlet. The distribution of fluid relative velocity has no obvious change under different solid volume fractions.

(4) As the volume fraction of solid phase increases, the friction and collision between media become more severe, thus the hydraulic loss increases and the lift decreases; As the proportion of solid phase increases, the mass flow of fluid increases and the lift increases. When the particle diameter is small, the reduction of head by the former is smaller than the increase of head by the latter. The combined effect of the two results in the head increasing with the increase of solid volume fraction.

Keywords: Centrifugal pump; Numerical simulation; Solid-liquid two-phase flow; Particle volume fraction

目录

摘要 I

Abstract II

目录 IV

第一章 绪论 1

1.1 课题研究背景和意义 1

1.1.1 课题研究背景 1

1.1.2 课题研究意义 1

1.2 离心泵的发展史及发展趋势 2

1.2.1 离心泵的发展史 2

1.1.2 离心泵的发展趋势 2

1.3 国内外研究现状 4

1.3.1 离心泵内单相流的研究现状 4

1.3.2离心泵内固液两相流的研究现状 5

1.3.3国内外对离心泵内气液两相流动研究现状概况 6

1.3.4离心泵内过流部件磨损研究现状 6

1.4 本文研究的主要内容 7

1.4.1问题的提出和意义 7

1.4.2 本文研究内容 7

第二章 固液两相流理论基础 8

2.1 固液两相流模型 8

2.1.1 单颗粒动力学模型 9

2.1.2 颗粒轨道模型 10

2.1.3 扩散模型 10

2.1.4 单流体模型 10

2.1.5 双流体模型 10

2.2 离心泵扬程及效率的计算 10

2.3 固液两相流中的运动方程 11

2.3.1 基本假设与理想状态下的运动方程 11

2.3.2 直角坐标系中离心泵叶轮处固液两相流的运动方程 12

第三章 基于固液两相流的离心泵实体建模 13

3.1 固液两相流离心泵Pro/E三维实体建模 13

3.1.1 叶轮的建模 14

3.1.2泵进口和叶轮内流体建模 14

3.1.3 压水室的建模 15

3.2 GAMBIT前处理 16

3.2.1 网格划分 16

3.2.2 边界条件与求解方法 16

第四章 固液两相流离心泵内流体流动特性分析 18

4.1 泵内流体流动特性分析 18

4.1.1 不同固相体积分数下的泵中截面静压力分布 18

4.1.2 不同固相体积分数下的泵中截面绝对速度分布 20

4.1.3 不同固相体积分数下的泵中截面相对速度矢量分布 22

4.2不同固相体积分数下离心泵的外特性 24

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